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NAME

       scandir, alphasort, versionsort - scan a directory for matching entries

SYNOPSIS

       #include <dirent.h>

       int scandir(const char *dirp, struct dirent ***namelist,
              int (*filter)(const struct dirent *),
              int (*compar)(const struct dirent **, const struct dirent **));

       int alphasort(const void *a, const void *b);

       int versionsort(const void *a, const void *b);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       scandir(), alphasort(): _BSD_SOURCE || _SVID_SOURCE
       versionsort(): _GNU_SOURCE

DESCRIPTION

       The  scandir()  function  scans the directory dirp, calling filter() on
       each directory entry.  Entries for which filter() returns  nonzero  are
       stored  in  strings allocated via malloc(3), sorted using qsort(3) with
       the comparison function compar(), and collected in array namelist which
       is  allocated  via  malloc(3).   If  filter  is  NULL,  all entries are
       selected.

       The  alphasort()  and  versionsort()  functions  can  be  used  as  the
       comparison function compar().  The former sorts directory entries using
       strcoll(3), the latter using strverscmp(3) on the strings  (*a)->d_name
       and (*b)->d_name.

RETURN VALUE

       The scandir() function returns the number of directory entries selected
       or -1 if an error occurs.

       The alphasort() and versionsort()  functions  return  an  integer  less
       than,  equal  to,  or  greater  than  zero  if  the  first  argument is
       considered to be respectively less than, equal to, or greater than  the
       second.

ERRORS

       ENOENT The path in dirp does not exist.

       ENOMEM Insufficient memory to complete the operation.

       ENOTDIR
              The path in dirp is not a directory.

VERSIONS

       versionsort() was added to glibc in version 2.1.

CONFORMING TO

       alphasort() and scandir() are specified in POSIX.1-2008, and are widely
       available.  versionsort() is a GNU extension.

       The functions scandir() and alphasort() are from 4.3BSD, and have  been
       available  under  Linux  since  libc4.   Libc4  and  libc5 use the more
       precise prototype

           int alphasort(const struct dirent ** a,
                         const struct dirent **b);

       but glibc 2.0 returns to the imprecise BSD prototype.

       The function versionsort() is a GNU extension,  available  since  glibc
       2.1.

       Since   glibc  2.1,  alphasort()  calls  strcoll(3);  earlier  it  used
       strcmp(3).

EXAMPLE

       #define _SVID_SOURCE
       /* print files in current directory in reverse order */
       #include <dirent.h>

       int
       main(void)
       {
           struct dirent **namelist;
           int n;

           n = scandir(".", &namelist, 0, alphasort);
           if (n < 0)
               perror("scandir");
           else {
               while (n--) {
                   printf("%s\n", namelist[n]->d_name);
                   free(namelist[n]);
               }
               free(namelist);
           }
       }

SEE ALSO

       closedir(3),   fnmatch(3),   opendir(3),   readdir(3),    rewinddir(3),
       seekdir(3), strcmp(3), strcoll(3), strverscmp(3), telldir(3)

COLOPHON

       This  page  is  part of release 3.35 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at http://man7.org/linux/man-pages/.